A white light-emitting device is formed by combining, for example, a luminescent material that emits red light by excitation with blue light, a luminescent material that emits green light by excitation with blue light, and a blue LED. The use of a luminescent material that emits yellow light having a luminescence peak in a wavelength range of 550 to 590 nm by excitation with blue light allows a white light-emitting device to be formed using fewer kinds of luminescent materials. As the yellow light-emitting luminescent material, for example a sialon is known.
Requirements of the luminous efficiency, the chromaticity, the temperature property and the luminescence emission spectrum half width are increasingly demanding for the yellow light-emitting luminescent material.